The present invention relates to a therapy endocavity probe with which tissues in particular of the prostate may be treated by pulsed and focused ultrasonic acoustic waves on the one hand, and these tissues may be viewed on the other hand.
In the state of the art, the use of an imaging transducer in association with a therapy transducer emitting focused ultrasonic waves is known, providing real-time follow-up of the tissues.
In the field of extracorporeal applications, there are various embodiments of probes with imaging. For example, Lizzi et al. in “‘Ultrasonic hyperthermia for ophthalmic therapy’ IEEE Trans. Ultrason., Ferroelec., Freq., Contr., 31, pp. 473-481” describe an echographic probe for an ophthalmologic application whereas Vallencien et al. (1996) in “‘Ablation of superficial bladder tumors with focused extracorporeal pyrotherapy’ Urology, 47, pp. 204-207” and Wu et al. in “‘Pathological changes in human malignant carcinoma treated with high-intensity focused ultrasound’, Ultrasound in Med & Biol., 27, pp. 1099-1106” propose extracorporeal probes with large sizes where the surface area occupied by the imaging transducer is negligible relatively to the surface area generating the ultrasonic waves.
If for extracorporeal applications, tissue imaging does not pose any particular problem, this is not the case for an endocavity probe such as an endorectal probe, considering problems notably related to the reduced bulk which such a probe should have. In order to attempt to solve this problem, Vaezy et al. in “Real-time visualization of high-intensity focused ultrasound treatment using ultrasound imaging”, Ultrasound in Med. & Biol., vol. 27(1), pp. 33-42, 2001” propose a probe including an imaging transducer located at the end of a therapy transducer. The main drawback of this probe lies in the fact that the axis of the image is not oriented along the focusing axis of the therapy transducer. Further, the relative positioning of both of these transducers does not facilitate its use under endocavity conditions.
Sanghvi et al. in their U.S. Pat. No. 5,117,832 propose an endocavity probe including a therapy transducer at the centre of which an imaging transducer is placed. To remedy the problem of the surface area loss of the therapy transducer, the imaging transducer is also used for therapy. Both transducers therefore have the same operating frequency or close operating frequencies which result from a compromise between the therapy frequency and the imaging one. The result is an altered image quality and/or treatment performances which are not optimum.
Also, the endorectal probe presented at the ISTU 2002 Congress by Ishida K, Kubota J, Mitake T, Carlson R F, Seip R, Sanghvi N T, Asuma T, Sasaki K, Kawabata K, Umemura S, in “‘Development and animal experiment of variable focusing HIFU system for prostate cancer treatment” includes an imaging probe with a rectangular shape, housed in the centre of the therapy probe. Even if such a probe is designed for endorectal application, its very large size precludes such an application in practice.
Analysis of known prior solutions leads to the observation that there appears the need for having a probe with dimensions allowing endocavity use, while being provided with a transducer capable of performing good quality imaging in real time, combined with a therapy transducer, with treatment performances which are not affected by the presence of the imaging transducer
In order to meet such a need, the applicants are worthy in that they sought a solution in the direct integration of the imaging transducer within the therapy transducer even if such a solution first leads to degradation of the therapeutic performance. Moreover, it was observed that this degradation of performance is accompanied by dispersion of acoustic energy, capable of generating undesirable secondary lesions. Surprisingly, a specific geometry between the imaging and therapeutic transducers, with which a probe may be made, which allows endocavity use, while providing real time follow-up and therapeutic effectiveness, was found in particular.